Latent Class Growth Anlaysis Quadrati... PreviousNext
Mplus Discussion > Growth Modeling of Longitudinal Data >
 Brian Don posted on Thursday, February 09, 2012 - 5:28 pm
I am conducting a latent class growth analysis with four time points and three classes. I originally tested a quadratic term for all classes using the following syntax:

CLASSES = c(3);
Analysis: type = MIXTURE;
STARTS = 100 10;
Model: %OVERALL%
i s q| RST1@0 RST2@3 RST3@6 RST4@11;

The quadratic term was only significant for one of the classes (e.g. class 1). Thus, I want to retain the quadratic term for Class 1 only and re-run the analysis. However, when I re-run the analysis after fixing the other two classes' quadratic term to zero, the classes seem to arbitrary switch so that Class 1 is no longer Class 1, and the quadratic term is fixed for the wrong two classes. Syntax for the second analysis:

Model: %OVERALL%
i s q| RST1@0 RST2@3 RST3@6 RST4@11;

Any help would be appreciated. Thanks!
 Linda K. Muthen posted on Friday, February 10, 2012 - 4:06 pm
The classes can change order. If you don't want this, you need to use starting values and STARTS=0;
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